David, I spent quite a few years doing auto body work, enough that the current prices of paint and labor shock me
I would get a couple gallons of Rustoleum in the color of your choice and have at it. I don't see where it would hurt the value, but it would enhance the appearance, and going down the road at 50 MPH no one will notice the roller marks
. You could apply some rustoleum primer, or if you only have a few bare spots the light gray spray primer from one of the dollar stores would spot repair.
Pressure wash it good before starting and of course let it dry well. (if it has been waxed you should use some silicone and wax remover before painting)
I actually did this to an old car I had to remove the vinyl roof from and it looked OK.
When you get to a certain point (if you are not doing a restoration) all you need is nice and function-able.
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